Method of purifying and sweetening hydrocarbons by copper halides



UNITED ST METHOD OF PURIFYING AND SWEETENING HYDROCARBONS BY COPPER HALIDES Walter A. Schulze and Frederick E. Frey, Bartiesville, Okla, assignors to Phillips Petroleum Company, Bartlesville, Okla.

No Drawing. Application February 28, 1931, Serial No. 519,258

14 Claims. (Cl.1963( FFHQE This invention relates to processes of treating gested reagents, the treated gasoline invariably gasoline and other hydrocarbon oils to sweeten contains soluble copper compounds. Other copthe same, and it comprises a process wherein the per sweetening solutions such as a mixture of gasoline or other hydrocarbon oil is treated with chloride and acetate, will sometimes give a gasosolutions of copper compounds in the presence line which is sweet to the doctor test immeof relatively high concentrations of bromide ions; diatelv after the treatment but, upon standing it more specifically comprises a process wherein in the presence of sodium plumbite and sulfur gasoline is sweetened with an aqueous solution Such a gasoline may develop a strong positive of copper sulfate and sodium bromide; and it doctor test, thus indicating that there are sulfur in further comprises processes wherein gasoline is compounds still in the gasoline which do not 6i treated with solutions of copper compounds in develop a positive doctor test until after standing. the presence of both bromide and chloride ions. In our prior copending application referred to In our copending application, Serial No. above, we have overcome the foregoing inherent 503,326. filed December 18, 1930, we have dedisadvantages and, asstated therein, employ copscribed and claimed processes wherein hydrocar per solutions containing relatively high concenl0 bon oils, for example, gasoline, are sweetened tretions of chloride ions. Our prior copending with copper compounds in the presence of a relaapplication, for example, describes treating gastively high chloride ion concentration. In that oline at ordinary room temperature, with an application, it is pointed out that the disadvanaqueous solution containing about eight percent tages inherent in the use of copper compounds of copper sulfate and about seventeen percent of '15 are avoided provided the chloride ion concentrasodium chloride. tion of the treating solution as well as the acidity In the present invention, we use sodium brothereof is controlled within certain limits, mlde or other soluble bromide in place of the We have now found that the sweetening in the sodium chloride described in the prior applicapresence of copper compounds, proceeds at a tion. somewhat faster rate if bromide ions are pres- More specifically, we treat a sour gasoline at ent, in fact, we find that adding a soluble bromide room temperature, say 20 or 25 C., with an such as sodium bromide to the solution of copper aqueous solution containing about thirteen persulfate containing sodium chloride as described cent by weight of copper sulfate pentahydrate 30 in the prior application increases the rate of and fifteen to twenty percent by weight of sodium sweetening over that when sodium chloride is bromide. When using sodium bromide instead used alone. of sodium chloride, the sweetening is more rapid As is well known, crude gasoline contains apand is complete within a minute or two at room preciable quantities of sulfur compounds, for extemperature. The treated gasoline is permanent- 35 ample, mercaptans, and one of the customary ly doctor sweet and free of copper compounds. 90 refining operations is the destruction or removal Instead of using sodium bromide alone, we find of such sulfur impurities. This process is comit advantageous to use a mixture of sodium bromOHlY referred to as sweetening. A swee mide and sodium chloride and replacement of a ened gasoline is sweet to the doctor test, in part of the sodium chloride, described in our co- 0 that it shows no discoloration when treated with pending application, and indicated above, by 5 an a kali Sodi P u S0111ti0n containing sodium bromide. decreases the time required for sulfur. complete sweetening.

Although plumbite solutions are still used to Our invention may also be practiced by the dia very large extent 8' sw t a d rect use of copper bromide and an aqueous solui reagent Still predominates in t fi y. tion containing about twenty percent of cupric 1 a number of t p have been made to utilize bromide can be used. However, when using cupric pp compounds- Copper Oxide and Salts of bromide alone, care must be taken that the brocopper have been suggested but. results have not mide ion concentration is approximately equal to been very satisfac ry- Reaction P oducts of that in a fifteen percent to twenty percent sodium oppe a Sulfur Compounds, oubted y o bromide solution whichmeans thatthe concentra- 5 complex structure and soluble to some extent in tion of copper bromide should be in the neighborgasoline, are sometimes formed. Furthermore, hood of twenty percent. Mixtures of cupric chlofollowing the directions of prior published procride and cupric bromide are also suitable and the esses, the sweetening action is incomplete. When sweetening is somewhat more rapid thanwhen.

using ammoniacal copper sulfate, one of the sugcupric chloride alone is used. no

, fifteen to twenty percent sodium bromide solution. The copper concentration in the treating solution can vary over rather wide limits, from, for example the chemical equivalent of the mercaptans to be destroyed up to fifteen or twenty percent, and in fact, good results are obtained.

- when the treating solution contains but one percent of copper sulfate and fifteen percent of sodium bromide. It is understood of course that the most economical copper concentration, as well as the bromide ion concentration will be determined for any particular gasoline to be treated. Aside from considerations of expense, the copper concentration can vary widely.

Various methods of mixing the treating solution with the gasoline can be used. Briskly agitating the two'together is satisfactory, although somewhat better results are obtained if the gasoline is allowed to issue from atomizers in the lower part of a body of treating solution. As the gasoline passes upward through the solution, it assumes a fine state of dispersion, and good contact of gasoline and treating solution is easily obtained in this manner. v

The volumetric ratio of treating solution to gas- ,oline can vary over wide limits, but when using ratios in the neighborhood of but one volume of solution to five or more of gasoline, better re sults are obtained if the acidity of the solution is kept between neutrality and one hundredth normal. Undesirable acidity tends todevelop when high ratios of gasoline to treating agent are employed, as well as when very low concentrations of copper, in the neighborhood of one percent, are used in the treating solution. In all cases, in our process, we work on the neutral or acid side and do not use alkaline copper solutions. A detrimental excess of acid is easily overcome by adding sufiicient alkaline material such as sodium hydroxide to the treating-solution when the acidity appears to a proach the upper limit stated. Acidity in excess of that stated is to be avoided, since it slows up the sweetening action, or even renders it incomplete. Our'treating agent works best in neutral or. slightly acid solutions. If de-' sired, the acidity of the treating solution can be ,controlled by adding a buffer substance such as sodium phosphate and a little mineral acid, say

hydrochloric, which will keep the acidity of the solution within desired limits. The use of buffer substances to control acidity is a common well understood procedure.

During thesweetening treatment with copper solutions containing bromide ionsas described above, we find it advantageous to introduce air or oxygen into the solution, while the sweetening action is progressing. the copper compounds and restore their activity, and when an oxidizing gas is used, little or no control of acidity is required.

After thegasoline or other hydrocarbon oil has been sweetened with cupric bromide, or an aqueous solution of copper sulfateand an alkali metal bromide, the gasoline is 'then given an ordinary water wash. Sometimes, after the water Wash,

the gasoline has a yellowish color. We have found that this may be removed by storing the oil after the water wash in the presence of a small amount of water for a few hours, or by This helps to regenerate washing the gasoline with an aqueous solution of soluble cyanide such as sodium cyanide.

After the gasoline has been sweetened in accordance with the foregoing, item be treated with sulfuric acid in ways well known to desulfurize the gasoline. We find that we can get increased desulfurization with sulfuric acid when the acid treatment follows our sweetening process. While the explanation of this is probably obscure, we believe that it is due to the fact that our sweetening process converts the mercaptans in the gasoline to disulfides and that these are more easily removed by the acid than are the mercaptans themselves.

This acid treatment step is carried out in the customary manner. For example, we can agitate the gasoline with about two and one-half pounds of 66 Baum sulfuric acid per barrel of gasoline,

, separate ofi the sludge and then wash the gasoline The gasoline may other soluble bromides, for example, potassium 1 0 bromide are, of course, suitable, but generally speaking, we find that from the economical point of view, an aqueous solution containing copper sulfate and sodium bromide is preferable. G'en erally speaking, the optimum concentration of bromide, whether it be derived froma soluble alkali metal-bromide, or from cupric bromide, is roughly equivalentto that contained in a fifteen to twenty percent sodium bromide solution. It

is to be understood, however, that we do not expressly limit ourselves to this concentration.

Some gasolines may require more or less bromide ion than that stated above.

When treating gasoline or other oils which v have received a preliminary treatment with sulfuric acid, it is best to intimately contact such oils with a solution of a cupric salt in strong alkali before sweetening the acid treated gasoline in accordance with the foregoing description. We

have found eifective for this purpose a solution of five percent copper sulfate in a thirty-five percent sodium hydroxide solution containing a stabilizer such as about three percent of glycerol or five to ten percent of cane sugar. After briefly contacting the acid treated gasoline with such an 125.

alkaline copper solution, we then apply our sweetening process as described.

Our invention is applicable to the treatment of cracked gasoline, kerosene and other hydrocarbon oils, natural gasoline, gaseous or liquefied natural gas, an arious hydrocarbon gases containing sulfur, and .the term hydrocarbon fluid in the appended claims as intended to be comprehensive. The removal of. hydrogen sulfide from a gas containing the same, can be achieved by the use of our treating solution by passing the I a A1- 4-: gas throng the solution in any one of'a number of ways. It is advantageous, for example, to

allow the gas and treating solution to flow in counter-current relation in a tower. Our treating solution destroys the hydrogen sulfide yielding elementary sulfur. When treating gases containing mercaptans, the organic disulfides be regenerated by simply blowing air therethroughor by adding if necessary a copper salt thereto and adjusting the bromide ionconcentration and acidity in accordance with the foregoing requirements. When regenerating the spent cupric solution with air or oxygen, it is best to work at a temperature of around 50 C. The regeneration of cupric chloride solutions is rapid at lower temperatures, but when regenerating cupric bromide solutions, we have found that moderately elevated temperatures give better results. The regeneration may also be accelerated by using air enriched with oxygen, air under pressure, or ozonized air. The spent treating solutions can be regenerated for use a number of times, and, after regeneration, are returned to the process. i

From the foregoing it is believed that the process may be readily understood by those skilled in the art, and it is apparent that various changes may be made in the steps of the process, without departing from the spirit of the invention, as expressed in the claims.

What is claimed and desired to be secured by Letters Patent is:

1. In the process of removing mercaptans and hydrogen sulfide from fluids containing the same, the step which comprises treating the fluid with an aqueous copper salt solution having a bromide ion concentration approximately equivalent to that in a fifteen to twenty percent solution of sodium bromide.

2. In the process of sweetening hydrocarbon fluids, the step which comprises treating the fluid with an aqueous copper salt solution having a bromide ion concentration approximately equivalent to that in a fifteen to twenty percent solution" of sodium bromide and maintaining the acidity of the solution during the treatment below one hundredth normal.

3. The process of sweetening hydrocarbon fluids, which comprises treating the fluid with an aqueous copper salt solution containing bromide and chloride ions in quantity approximately equivalent to that in a fifteen to twenty percent solution of a mixture of sodium bromideand chloride.

4. The process of sweetening hydrocarbon fluids, which comprises treating thefluid with an aqueous copper salt solution containing bromide and chloride ions in quantity approximately equivalent to that in a fifteen to twenty percent solution of a mixture of sodium bromide and chloride, and maintaining the aciditypof the copper solutionduring treatment between neutrality and one hundredth normal.

5. The process of sweetening hydrocarbon fluids, which comprises treating the fluid with an aqueous copper bromide solution having a bromide ion roncentration approximately equivalent bromide, and maintaining the acidity of the solutherewith.

to that in a fifteen to twenty percent solution of sodium bromide.

6. The process of sweetening hydrocarbon fluids, which comprises treating the fluid with an aqueous copper salt solution containing bro-- mide and chloride ions the concentration of which is approximately equivalent to that in a fifteen to twenty percent solution of a mixture of sodium bromide and chloride, and maintaining the acidity of the copper solution between neutrality and one hundredth normal. 1-

7. The process of sweetening gasoline, which comprises treating the gasoline with an aqueous solution of copper sulfate and alkalimetal bromide, the halogen ion concentration in-the solution being approximately equivalent to that in a fifteen to twenty percent solution of sodium bromide.

8. The process of sweetening gasoline, which comprises treating the gasoline with an aqueous solution of copper sulfate and alkali metal bromide, the halogen ion concentration in the solution being approximately equivalent to that in a fifteen to twenty percent solution of sodium tion between neutrality and one hundredth normal. 9. The process of sweetening gasoline, which comprises treating the gasoline with'an aqueous solutionof copper bromide. having a bromide ion concentration approximately-equivalent to that in a fifteen to twenty percent sodium bromide solution.- I e 10. The process of sweetening gasoline, which comprises treating the'gasoline with an aqueous solution of coppei bromidehaving a bromide ion concentration approximately equivalentfito that in a fifteen to' twenty percent sodium bromide solution, and maintaining the acidity of the solution between neutrality and one-hundredth normal. I

11. The process as in claim 7, wherein an oxygen containing gas is introduced into the copper solution during the treatment of the gasoline 12. The processas in claim .'7',l wherein the sweetened gasoline'is treated with sulfuric acid to, desulfurize the gasoline. 1

13. The 1 process of sweetening hydrocarbon fluids which comprises treating the fluid with an aqueous copper salt solution containing a total bromide plus chloride concentration approximately equal to the halogen concentration in a fifteen to twenty per cent solution of sodium bromide. I

14. The process set forth in claim 3, wherein a gas containing free oxygen ispassed-into said solution, whereby the-latter is regenerated.

WALTER A. SCHULZE. FREDERICK E. FREY. 

